NAME
Path::ScanINC - Emulate Perls internal handling of @INC.
VERSION
version 1.000000
SYNOPSIS
The Aim of this module is to fully implement everything Perl does with
@INC, to be feature compatible with it, including the behavior with
regard to "sub refs" in @INC.
use Path::ScanINC;
# Normal usage.
my $inc = Path::ScanINC->new( );
# In case you need something that isn't @INC
# but works like it
my $inc = Path::ScanINC->new( inc => \@INC );
# Freeze the value of @INC at the time of object instantiation
# with regard to behaviour so later changes to @INC have no effect
my $inc = Path::ScanINC->new( immutable => 1 );
# Return the first file in @INC that matches.
my $file = $inc->first_file('Path', 'ScanINC.pm' );
# Find all possible versions of modules in @INC
my ( @files ) = $inc->all_files('Path', 'ScanINC.pm');
# Try to discover a File::ShareDir 'module' root.
my $dir = $inc->first_dir('auto','share','module');
# Should return the same as File::ShareDir::module_dir('Path::ScanINC')
# ( assuming such a directory existed, which there is presently no plans of )
my $dir = $inc->first_dir('auto','share','module','Path-ScanINC');
# Find All File::ShareDir roots in @INC
my ( @dirs ) = $inc->all_dirs('auto', 'share');
REF SUPPORT IN @INC
This module has elemental support for discovery of results in @INC using
"CODE"/"ARRAY"/"BLESSED" entries in @INC. However, due to a limitation
as to how "perl" itself implements this functionality, the best we can
do at present is simply return what the above are expected to return.
This means if you have any of the above ref-types in @INC, and one of
those returns "a true value", you'll get handed back an "ARRAY"
reference instead of the file you were expecting.
Fortunately, @INC barely ever has refs in it. But in the event you
*need* to work with refs in @INC and you expect that those refs will
return "true", you have to pick one of two options, either :
a. Write your code to work with the "array-ref" returned by the
respective reference on a match
b. Use the "all_" family of methods and try pretending that there are no
"array-refs" in the list it returns.
Its possible in a future release we may have better choices how to
handle this situation in future, but don't bet on it.
Given that the API as defined by Perl mandates "code-ref"'s return lists
containing "file-handles" or iterative "code-ref"'s , not actual files,
the best I can foresee at this time we'd be able to do to make life
easier for you is creating a fake library somewhere in a "tempdir" and
stuffing the result of the "code-ref"'s into files in that directory
prior to returning a path to the generated file.
( And it also tells me that they have to be "Real" file handles, not
tied or blessed ones, so being able to ask a "filehandle" what file it
represents is equally slim.... if that is of course what you require )
For more details, see "perldoc perlfunc" or "perldoc -f require" .
METHODS
new
my $object = $class->new(
inc => [ 'x', 'y', 'z' , ],
immutable => 1 | undef
);
immutable
if( $inc->immutable ) {
print "We're working with a snapshotted version of @INC";
}
inc
for my $i ( $inc->inc ) {
say "Plain: $incer" if not ref $incer;
say "Callback: $incer" if ref $incer;
}
Returns a copy of the internal version of @INC it will be using.
If the object is "immutable", then this method will continue to report
the same value as c, or will be updated every time the original
array reference passed during construction gets updated:
my $ref = [];
my $a = Path::ScanINC->new( inc => $ref );
my $b = Path::ScanINC->new( inc => $ref, immutable => 1 );
push @{$ref} , 'a';
is( [ $a->inc ]->[0] , 'a' , "non-immutable references keep tracking their original" );
isnt( [ $b->inc ]->[0] , 'a' , "immutable references are shallow-copied at construction" );
Do note of course that is a SHALLOW copy, so if you have multiple @INC
copies sharing the same "array"/"bless" references, changes to those
references will be shared amongst all @INC's .
first_file
if( defined ( my $file = $inc->first_file('Moose.pm') ) {
print "Yep, Moose seems to be available in \@INC , its at $file, but its not loaded (yet)\n";
}
This proves to be a handy little gem that replaces the oft used
if( try { require Moose ; 1 } ){
Yadayadayada
}
And adds the benefit of not needing to actually source the file to see
if it exists or not.
IMPORTANT: PORTABILITIY
For best system portability, where possible, its suggested you specify
paths as arrays of strings, not slash-separated strings.
$inc->first_file('MooseX' , 'Declare.pm') # Good
$inc->first_file('MooseX/Declare.pm') # Bad.
This is for several reasons, all of which can be summarized as
"Windows".
* %INC keys all use Unix notation.
* @INC callbacks expect Unix notation.
* "\" is a valid path part on Unix.
* On Win32, we have to use "\" Separation, not "/" for resolving
physical files.
The sum of these means if you do this:
$inc->first_file('MooseX/Declare.pm')
On win32, it might just end up doing:
C:\some\path\here/MooseX/Declare.pm
Which may or may not work.
And additionally, if the above module is loaded, it will be loaded as
"MooseX/Declare.pm"
in %INC, not what you'd expect, "MooseX\Declare.pm"
all_files
Returns all matches in all @INC paths.
my $inc = Path::ScanINC->new();
push @INC, 'lib';
my ( @files ) = $inc->all_files('Something','Im','Working','On.pm');
pp(\@files );
# [
# '/something/........./lib/Something/Im/Working/On.pm',
# '/something/....../share/per5/lib/site_perl/5.15.9/Something/Im/Working/On.pm',
# ]
Chances are if you understand how this can be useful, you'll do so
immediately.
Useful for debugging what module is being loaded, and possibly
introspecting information about multiple parallel installs of modules in
%ENV, such as frequently the case with 'dual-life' modules.
perl -MPath::ScanINC -E 'my $scanner = Path::ScanINC->new(); say for $scanner->all_files(qw( Scalar Util.pm ))'
/usr/lib64/perl5/vendor_perl/5.12.4/x86_64-linux/Scalar/Util.pm
/usr/lib64/perl5/5.12.4/x86_64-linux/Scalar/Util.pm
Sort-of like ye' olde' "perldoc -l", but more like "man -a"
I might even be tempted to make a sub-module to make one-liners easier
like
perl -MPath::ScanINC::All=Scalar/Util.pm
REMINDER: If there are "REFS" in @INC that match, they'll return
"array-ref"'s, not strings.
first_dir
Just like "first_file" except for locating directories.
all_dirs
Just like "all_dirs" except for locating directories.
AUTHOR
Kent Fredric
COPYRIGHT AND LICENSE
This software is copyright (c) 2014 by Kent Fredric .
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.